1. Field of the Invention
The present invention relates to an optical device, and more particularly, to an integrator of an optical device. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for enhancing the optical efficiency in the optical device using a color drum.
2. Discussion of the Related Art
Depending upon the number of image display devices used, an optical device can be categorized as a single-chip optical device, a two (2)-chip optical device, and a three (3)-chip optical device. Herein, the three (3)-chip optical device has a large number of optical assembly parts and includes an illuminating part as well as a relay part for compensating a difference in the optical path. Accordingly, the three (3)-chip optical device is disadvantageous in having a complicated structure and a large size.
Also, the light generated from a lamp of the three (3)-chip optical device lacks red light rays. Thus, since the color purity of the color red is low, a color gamut (i.e., the capacity of representing colors) becomes narrow. Moreover, since the three (3)-chip optical device uses a large number of image display device, the device cost increases and alignment problems of red, green, and blue panels occur.
Therefore, in order to resolve such problems of the three (3)-chip optical device, the two (2)-chip optical device or the single-chip optical device are more widely used in recent technology.
The two (2)-chip optical device and the single-chip optical device require a device for color scrolling, such as a color wheel, a color drum, a transmissive color drum, a color switch, and a rotating prism. Herein, the color drum is the most widely used scrolling device for its low cost and ability to easily form the optical device. Also, the color drum is advantageous in that, during a color scrolling process, a boundary surface of each color section of the color drum moves in a linear form.
However, in the optical device using the color drum, the shape of an integrator is limited due to the structural characteristic of the color drum. Herein, the integrator allows the light generated from the lamp to be spatially uniform and also changes the polarization direction of the generated light.
Unlike in the optical device using a color wheel, in the optical device using the color drum, the light generated from the lamp is passed (or transmitted) through the integrator at a direction forming a right angle (90°) with the direction of the light when received at the integrator, so as to reach the surface of the color drum.
Since the light outputted from the integrator is flown towards a color filter section of the color wheel, the integrator used in the color wheel optical device is not problematic. However, the light outputted from the integrator used in the color drum may not be accurately aligned with the color filter section of the color drum.
As described above, due to the structural limitations in the color drum and the integrator, the related art color drum optical device has the problem of a deficient optical efficiency.